Drawer slide assemblies are necessary components for sliding drawers for suspending and sliding the drawers within cabinets and appliances.
Drawer slide assemblies typically comprise two rail slide assemblies, each of which are mounted to a side of the drawer and to the inside walls of an opening in the appliance. The rail slide assemblies are mounted on either side of the sliding path of the drawer. Such an assembly usually comprises an inner channel rail that is attached to the drawer and an outer channel rail that is attached to the rest of the piece of kitchen, household or office furniture. There can also be one or more intermediate channel rails that act as an interface between the inner and outer rails. Sliding means such as ball bearings allow the rails to slide relative to one another. The sliding motion is limited between a fully retracted position (closed) and a fully extended position (open), provided that there are stop levers at the fully closed and fully open positions.
It is often desirable that the drawer, once in its retracted position, require some resistance to be reopened. In order that a drawer does not inadvertently come partially open, catch mechanisms can be used to hold or bias the drawer in its closed position. In the kitchen appliance field, this may be particularly beneficial, since leaks of liquid, food, vapours, smells, heat and cold should be kept to a minimum.
Catch mechanisms composed of springs, hooks, latches, magnets or fittings are found in the prior art. However, mechanisms with sufficient heat resistance for adequately securing a drawer in a fully retracted position in elevated temperature conditions, such as those occurring in stoves, are lacking in the prior art. Catch mechanisms have usually been made of plastic or rubber materials, the properties of which change at high temperatures so that the ability of the catch mechanism to maintain the slide assembly in a retracted position is hindered. Formal deformation, plastic deformation and melting are some problems with rubber and plastic catch mechanisms in stoves.
Some fittings in the prior art are composed of a projection made of elastic material such as rubber mounted to the outer rail, and a recess made of metal and which is part of the inner rail. When the inner rail retracts, the two components fit together and hold the inner rail in its retracted position with some resistance.
There also exists in the prior art a two part spring assembly for latching the inner rail to the outer rail in the former's fully retracted position. This catch mechanism comprises a catch point of the inner rail and a two part spring mounted on the outer rail, one part of which being mounted via a pivot point. The two part spring is also made of plastic. A main problem associated with this two part spring catch mechanism is that the plastic material is susceptible to detrimental changes in properties due to heat, and consequently the functioning of the plastic two part combination can be hindered by excessive heat.
Magnets have also been used to secure drawers in a closed position. In this mechanism, two attractive magnets, or one magnet and another element made of magnetically susceptible material such as steel, which will be referred to as magnetic elements, are attached to the inner and outer rails between them, so that in the fully retracted position the magnetic elements touch and thus require a certain force to overcome the magnetic force and reopen the drawer. In the prior art, the magnetic elements have been substantially rigidly fixed to their respective inner and outer rails, which means that they may not be in flush contact with each other when the drawer is closed. When the magnetic elements are not completely flush their attractive force and thus their resistive effect to extension is greatly reduced. It is also difficult to consistently produce appliances, whose parts are completely aligned when the parts are rigidly fixed to each other. Furthermore, when a wide range of temperatures, including elevated temperatures, is experienced, one or more parts of the appliance, drawer, or drawer slide assembly may warp slightly. Such warping effects may cause formerly flush magnetic elements to become uneven. The effect of heat can thus be detrimental to this kind of drawer slide catch mechanism.
The U.S. Pat. No. 4,932,792 (BAXTER), U.S. Pat. No. 5,671,988 (O'NEILL) and U.S. Pat. No. 6,435,636 (MacMILLAN) describe catch mechanisms for retaining a drawer in a closed position. They disclose mechanisms comprising flexible or compressible arms combined with projections that combine to offer a resistance to opening a drawer from the closed position.
The U.S. Pat. No. 5,248,195 (SHIN et al.), U.S. Pat. No. 4,560,212 (PAPP et al.) and U.S. Pat. No. 4,441,772 (FIELDING et al.) describe catch mechanisms with various mechanical constructions. SHIN et al. and PAPP et al. describe a catch mechanism comprising a latch element that functions with an alternating movement about a pivot point when the drawer is closed. FIELDING et al. describe a rotating latch element that hooks onto a projection, but the purpose of the mechanism is not to retain and bias a drawer in a closed position.
Catch mechanisms should also be able to compensate for the tolerance in drawer fabrication. Thus greater leeway can be achieved in drawer production and functioning.
As conditions of high, low and changing temperatures are especially common within kitchen appliances, an internal catch mechanism for a drawer slide assembly should be able to withstand such conditions in such equipment as, for example, a stove. Increasing the heat resistance of drawer slide assemblies will decrease excessive wear on and maintain proper functioning of the composing parts, and will be advantageous to consumers and users of the equipment.